3-Hydroxyisobutyryl-CoA Hydrolase Deficiency
Autosomal recessive
Caused by changes in both copies of the HIBCH gene, which makes an enzyme in the valine breakdown pathway. It is a rare mitochondrial disorder of valine metabolism.
Signs and symptoms
Usually begins in infancy with low muscle tone, feeding difficulties and developmental delay, often followed by episodes of neurological deterioration. Brain imaging typically shows changes in the basal ganglia similar to Leigh syndrome, and movement problems such as dystonia are common. Seizures and eye movement problems can also occur.
What a diagnosis changes
Care is led by a metabolic specialist and may include a valine-restricted diet, alongside physiotherapy and developmental support; preventing catabolism during illness may help. Both parents are usually carriers, so genetic counselling and carrier testing for relatives are offered.
Genes analysed
Also known as
Beta-hydroxyisobutyryl-CoA deacylase deficiency; HIBCH deficiency; HIBCHD; methacrylic aciduria; neurodegeneration due to 3-hydroxyisobutyryl-CoA hydrolase deficiency
